Power transmission



Patented Aug. 26, 1941 UNITED STATES PATENT OFFICE 2,253,653 I rowan TRANSMISSION James Robinson and Rudolf E. Esch, Detroit, Mich., assignors to Vickers Incorporated, De-

troit,'Mic h., a corporation of Michigan This invention relates to power transmissions and more particularly to those of the fluid type wherein a power transmitting fluid, such as oil,

and hereinafter referred to as such, is utilized for the transmission of. power between one or more pumps and one or more fluid motors.

This invention is particularly concerned with a transmission adapted for driving a wire drawing apparatus with improved efficiency and faciltermined fraction of the forward-pull. Since the forward-pull inherently fluctuates a certain amount, it is difficult to provide a proportional variation in the back-pull by the use of friction rake mechanism, etc. The use of a brake to reate the back-pull on the wire is also disadantageous in that the work done at the brake is completely dissipated.

It is anobject of the present invention to provide a power transmission system particularly adapted for drawing wire in this manner and which avoids the difficulties experienced with previous apparatus.

Application March 10, 1938 Serial No. 195,189 9 Claims. (01. 205-1 1) ing drawing wherein a preferred form of the present invention is clearly shown.

In the. drawing:

.The single figure represents a diagrammatic view of a wire drawing "pparatus and-its associated power transmission system incorporating a preferred form of the present invention.

The drawing apparatus may comprise a pulling reel l having a drive shaft 12 and a holdback reel l4 having a drive shaft l6. Intermediate the two reels a suitable drawing die I8 is mounted on the bed of the machine and the wire to be drawn, indicated at 22, is threaded around the reel I4 through the die l8 and around the reel l0 whereby the wire 22 may be drawnthrough the die l8. 1

For the purpose of driving the shafts l2 and IS in the required manner, a hydraulic power transmission system is provided, comprising a variable displacement pump 24 having a suction conduit 26 communicating with an oil tank 28. The pump 24 delivers oil to a delivery conduit 30 at a rate depending upon the setting of a pivoted yoke 32, movable between the position shown and the position determined by the adjustable stop 33ias is well known in the art. A suitable prime mover, such as an electric motor 34, is connected to the drive shaft 36 of the pump 24 to operate the same at a constant speed. Communicating with the discharge conduit 30, by meansof a by-pass conduit 38, is a pilot operated relief valve 40 adapted to discharge oil to A further object is to provide a power transmission of thischaracter wherein the hold-back sion is not dissipated, but is utilized in driving the machine as a whole.

It is also an object of the invention to provide a transmission system for the purposes described, which is simple and automatic in its operation, which may be readily started with gradual pickup in speed and which may be operated forwardly or backwardly with equal facility and which may be operatedintermittently in small steps under complete manual control of the operator.

A further object is to provide a transmission system for this purpose which is readily adjustable to take care of differentsizes of wire and different amounts of area reduction at the die.

It is also an object to provide a novel method and apparatus for drawing wire.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanythe tank through a conduit 42 whenever a predetermined pressure exists in the conduit or whenever the control chamber 44 of the valve -is connected to tank through the venting conduit 46. The valve 40 may be similar in construction to that disclosed in the patent to Harry F. Vickers, #2,043,453. The conduit 30 extends through a check valve 48 'to the pressure connections of a pair of variable displacement fluid motor units 50 and 52, the drive shafts 54 and 56 of which and 68 are connected with control levers l0 and 12 for manually adjusting the displacement of the motor units 50 and 52. The tank connections of the motor units connect by conduits 14 and 16 with the cylinder ports of a solenoid operated, closed center, four-way valve 18. The pressure and tank ports of the valve "connect to the tank 28 by conduits and 82. The spool 84 of the valve 18 is connected by a lever 86 to. a pair of solenoids 88 and 90. The solenoid 88 when" energized shifts the lever 86 to the left, opening both conduits l4 and Hi to communication withthe tank. When the solenoid 90 is energized the lever 86 is shifted backto the position shown in the drawing, wherein all ports in the valve 18 are blocked. A dashpot 9I may be provided for retarding movements of the valve spool 84. I

Branch conduits 92 and 94 connect the conduits 14 and 16 with relief valves 96 and 98 adapted to discharge oil to the tank through conduits I and I02 whenever a predetermined pressure is exceeded in the conduits 92 and 94. Branch conduits I04 and I06 also communicate with the conduits 14 and 16 and connect through the check valves I08 and H0 with a conduit II2 leading to the tank conduit I02. The check valves I08 and H0 open to free flow of oil from the tank into the conduit I04 and the conduit I06 respectively.

In open communication with the branch conduits 92 and 94, through the pressure chambers of the relief valves 96 and 98 are a pair of conduits H4 and H6 leading to the cylinder ports of a closed center, spring centered, solenoid operated, four-way valve I I8. The pressure port of the valve H8 is plugged while the tank-ports thereof connect to the tank 28 by a conduit I20. A solenoid I22 is adapted to shift the spool I24 of the valve II8 to the left when energized and thus connect the conduit II6 to the conduit I20 leaving the conduit II4 blocked by its communication with the blocked pressure port. A solenoid I26 is adapted, when energized, to shift the spool I24 to the right making the opposite connections.

For the purpose of controlling the position of the yoke 32 of the pump 24, a control cylinder I28 has a piston I30 connected by a link I32 to the yoke 32. The upper end of the cylinder I28 communicates by a conduit I34 with the left hand cylinder port of a solenoid operated, spring offset, closed center, four-way valve I36. The lower end of the cylinder I28 communicates by a conduit I38 with the right hand cylinder port of the valve I36. Interposed in the conduit I38 is a restriction I40 around which a by-pass I42, controlled by a check valve I44, permits free flow of oil out of the lower end of the cylinder I28. The pressure port of the valve I36 connects by a conduit I46 through a relief valve I48 to the delivery port of a small fixed displacement pump I50 driven from the motor 34 by a belt I52. The suction port of the pump I50 and the tank port of the valve I36 are connected to tank by conduits I54 and I56. The relief valve I48 is adapted to discharge oil to the tank through a conduit I58 whenever a predetermined pressure is exceeded in the conduit I46.

The vent conduit 46 of the valve 40 is under the control of a spring ofiset, solenoid operated, closed center, four-way valve I60 to the pressure port of which the conduit 46 connects. One cylinder port of the valve I60 is plugged while the other connects to the tank conduit I58 by a branch I62. The tank port of the valve I60 connects to tank conduit I02 by a branch I64. The fluid motor units 50 and 52 may be enclosed in suitable casings I66 and I68 which are connected to the branch conduit I64 by a conduit I10.

For the purpose of controlling the various solenoid operated valves, an electric circuit is provided as follows:

A suitable magnetic starting contactor I12 connects to a three-phase alternating current supply line I14 and controls the supply of current to the motor 34 through the load line I16. A conductor I18 leads to starting switch I80 adapted, when depressed, to connect the conductor I18 with a conductor I82, leading to the contactor I12 and forming the starting circuit therefor in the well known manner. The customary stopping circuit includes the conductor I82 nd a normally closed stop switch I84, which connects by a conductor I86 with the contactor I12. The starting and stopping switches I88 and I84 each have auxiliary contacts adapted to be closed when their respective push buttons are depressed, the auxiliary circuits for both switches being connected to one leg of the supply line I14 by a. conductor 200. The auxiliary circuit for the switch I88 connects by a conductor 202 and manual switch 204 with a conductor 208 leading to. the solenoid 88. The auxiliary circuit for the switch I84 connects by a conductor 208 with the solenoid 90. The opposite sides of the solenoids 88 and 90 are connected by a conductor 2I0 with a conductor 2I2 leading to another leg of the supply line I14. The conductor 2I2 extends to a pair of normally opened inching switches 2I4 and 2I6, the opposite sides of which connect to the solenoids I22 and I26 respectively. The other sides of the solenoids connect by a conductor 2I8 with the supply line I14 at the conductor 200. The solenoids of the valves I36 and I60 are connected directly across two legs of the load line I16 for energization concurrently with energization of the motor 34.

In operation, with the wire 22 wrapped around the reels I0 and I4 and threaded through the die I8, and with the yokes 62 and 64 adjusted to positions, as illustrated, with the yoke 64 at a smaller displacement than the yoke 62, the motor 34 may be started by depressing starting switch I80. Previous to this the solenoid valve I36 was deenergized and lies in the position shown, and the yoke 32 was moved to neutral position, illustrated, by the piston I30. Closure of the starting circuit I18-I82 causes the contactor I12 to energize the load lines I16 starting the motor 34 and energizing the solenoid valves I36 and I60. At the same time the second circuit of the starting switch I closes a circuit l to the solenoid 88 extending from the supply line I14 through conductor 200, switch180, conductor 202, switch 204, which should be closed for normal operation, conductor 206, solenoid 88 and conductors 210 and 2I2 to the line I14. The valve spool 84 is accordingly shifted to the left connecting conduit 14 to conduit 80 and connecting conduit 16 to conduit 82. As the motor starts the pumps 24 and I50 are caused to operate and the solenoid valves I36 and I60 shift to the right and left respectively. Shifting of the former causes fluid delivered from the pump I5I through conduit I46 to be directed to the conduit I38 and through restrictor I40 to the bottom end of cylinder I28. The yoke 32 is thus moved upwardly by the piston I30 at a speed determined by the restriction I40. Shifting of the valve I60 closes the vent line 46 thus permitting relief valve 40 to close and causing pressure oil, delivered by the pump 24, to continue on through the conduit 30, and check valve 48 to the motors 50 and 52. The rate of delivery of oil by the pump 24 increases gradually as the yoke 32 moves upwardly until it abuts the adjustable stop 33.

It will be noted that the motors 50 and 52, when their yokes are adjusted, as shown in the drawing, are connected for operation in opposite directions, that is, if the wire 22 were not connecting the reels I0 and I4, the shafts I2 and 54 would rotate in "the directions shown by the arrows while the shafts i6 and 66 would rotate in the opposite direction to that of the arrows shown on the drawing. Since the wire 22 connects the two reels together for substantially synchronous operation and since the yoke 64 is adjusted to a lesser angle than the yoke 62 the backward torque available at the shaft 56 with a given pressure in the conduit 30, is less than the forward torque available at the shaft 54. Accordingly, the motor 50 is able to drive the reel I forwardly, pulling the wire 22 through the die and also pulling the reel I4 forwardly, overcoming the backward torque of the motor 52 and driving the same so that it operates as a pump delivering oil into the pressure line against the pressure head existing therein. The motor 52 withdraws oil for this purpose from thetank through conduit I02, conduit 82, valve I8 and conduit 16'. Oil delivered by both pump 24 and motor 52 into the pressure line 30 passes through the motor and discharges through conduit I4, valve I8 and conduits 80 and I02 to the tank.

There is thus produced a hold-back tension on the wire 22 between the die I8 and the reel I4. The relative values of the tension in the wire on either side of the die I8 depends upon the relative settings of the yokes 62 and 64, and may be freely varied as desired and as determined by experience under various drawing conditions. If the angle of the yoke 64 be increased relative to that of 62, the hold-back tension will be increased relative to the pulling tension. With any given setting of 'the yokes 62 and 64, however, it will be noted that a constantratio is maintained between the tension in the wire entering the die and that in the wire leaving the die. This ratio is maintained even though the resistance at the die I8 varies from moment to moment as may occur due to variations in lubrication at the die or due to variations in the characteristics of the metal along the length of a given piece of wire.

When it is desired to stop the machine the stop switch I84 may be depressed, opening the stopping circuit I82I86 and causing the contactor 4 I12 .to deenergize the load line I I6. The solenoid valves I36 and I shift to the left and right under their spring bias and the motor- 34 coasts to a stop. Sufficient oil will be delivered by the pump I50 before the motor 34 comes to a stop to move the yoke 32 to neutral position by delivering oil to the'conduit I46, valve I36 and conduit I34 to the upper end of cylinder I28. Oil returning from the lower end of cylinder I28 passes freely through the conduits I38 and I42,

. check valve I44, and valve I36 to the tank conduit I56. Shifting of the valve I60 again vents the relief valve 40, relieving pressure in the conduit 30.

The depression of the stop switch I84 also energizes the solenoid 90 through conductor 200,

The inertia of the reel I4 tends to drive the motor 52 in the same direction in which it has been previously driven and thus causes it to continue to act as a pump, delivering oil into the conduit 30. This oil passes to the motor 50 through the conduit 30 and is prevented from by-passing to tank through conduit 38 and relief valve 40 by the check va1ve40. The motor 52 may withdraw oil from the tank under these conditions through conduit II2, check valve H0 and conduits I06 and 16.

The machine may be operated to draw wire in the opposite direction by using an oppositely 'facing die I8 and by adjusting the yoke 64 to increments for inching, the switch 204 may be opened and :the starting switch I depressed to start the motor as before, except that the valve spool 84 remains in its blocking position. Un-

cation between conduits I I4 and I20. The mo- I tor 50 is (thus permitted to discharge oil to the switch I 84, conductor 208, solenoid and conductors 2I0 and 2I2 to the line I14. The valve spool 84 is accordingly returned to the position tank through, conduits I4, 92 and H4 and the reel operates in the normal manner so long as the switch I4 is closed. If the yokes 62 and 64 are adjusted for operation in 'the reverse direction the switch 2I4 is operated for inching movement to produce the safe effect by exercising control on the discharge line II6 from the motor 52.

The transmission system of the present invention may also be utilized for drawing machines where there are more than two reels in series, and where it is desired to operate one'or more intermediate reels, the reel I4 for example, as a hold-back reel for the wire leaving the reel and as a pullingreel for the wire approaching the reel. An example of such an arrangement is illustrated by' the additional reel 220 which feeds wire to the die 222 ahead of the reel I4. The reel 220 may be either freely rotatable or may be provided with suitable brake mechanism such as a friction brake or a hold-back motor similar to .rthe motor 52and connected in parallel therewith. All that is necessary to operate the ap-- pa'ratus in this manner is to shift the -yoke 64 downwardly to the dotted line position thus causing the motor 52 to operate as a motor for drivreel I0.

braking effect causing the machine to slow down' and come to a stop in a reasonably short period.

1. A drive system for a wire drawing machineof the type having a drawing reel and a holdback reel and a drawing die intermediate the reels comprising in combination with a source of power, fluid pressure energy translating devices connected to operate each reel, and a circuit connecting said translating devices in parallel with the source of power, whereby the drawing reel will be driven by its translating device and the hold-back reel will be driven from the drawing reel through the medium of the wire being drawn, the translating device at the hold-back reel serving to cause a predetermined back-pull on the wire entering the die.

2. A drive system for a wire drawing machine of the type having a drawing reel and a holdback reel and a drawing die intermediate the reels comprising in combination with a source of power, afiuid pressure energy translating device connected to operate the drawing reel, a circuit connecting the translating device with the source, and means for causing a predetermined back-pull on the wire entering the die comprising a second fluid pressure energy translating device mechanically connected to the hold-back reel and connected into said circuit in a manner to return the energy of the hold-back reel to the circuit.

3. A drive system for a wire drawing'machine of the type having a drawing reel and a holdback reel and a drawing die intermediate the reels and a drawing die beyond the hold-back reel comprising in combination with a source of power, fluid pressure energy translating devices connected to operate each reel, and a circuit connecting said translating devices in parallel with the source of power, whereby the drawing reel will be driven by its translating device and the hold-back reel will be driven from the drawing reel through the medium of the wire bein drawn, the translating device at the hold-back reel serving to apply a portion or the required torque to the hold-back reel whereby a predetermined back-pull from the second mentioned die is transmitted to the wire entering the first mentioned die.

4. A drive ystem for a wire drawing machine.

of the type jving a drawing reel and a holdback reel and a drawing die intermediate the reels comprising in combination with a pump, fluid pressure energy translating devices connected to operate each eel, and a circuit connecting said translating devices in parallel with the pump, whereby the drawing reel will be driven by its translating device and the holdback-reel will be driven from the drawing reel through the medium or the wire being drawn, the translating device at the hold-back reel serving to cause a predetermined back-pull on the wire entering the die and means controlling the rate of fluid delivery to the translating devices.

5. A drive system for a wire drawing machine of the type having a drawing reel and a holdback reel and a drawing die intermediate the reels comprising in combination with a" pump, fluid pressure energy translating devices connected to operate each reel, and a circuit connecting said translating devices in parallel with the pump, whereby the drawing reel will be driven by its translating device and the holdback reel will be driven from the drawing reel through the medium of the wire being drawn, the translating device at the hold-back reel serving to cause a predetermined back-pull on the wire entering the die, and means controlling the rate cit-fluid delivery to the translating devices,

said means including a movable member and means for moving said member at a predetermined slow rate to start the machine with a gradual acceleration.

6. A drive system for a wire drawing machine 01' the type having a drawing reel and a holdback reel and a drawing die intermediate the reels comprising in combination with a source of power, fluid pressure energy translating devices connected to operate each reel, one of said devices being of the variable displacement type, and a circuit connecting said translating devices in parallel with the source of power, whereby the drawing reel will be driven by its translating device and the hold-back reel will be driven from the drawing reel through the medium of the wire being drawn, the translating device at the hold-back reel serving to cause a predetermined back-pull on the wire entering the die and means for adjusting the displacement of said one device.

7. A drive system for a wire drawing machine of the type having a drawing reel and a holdback reel and a drawing die intermediate the reels comprising in combination with a source of power, a fluid pressure energy translating device connected to operate the drawing reel, a circuit connecting the translating device with the source, and means for causing a predeterminedback-pull on the wire entering the die comprising a second fluid pressure energy translating device 01 the variable displacement type and mechanically connected to the hold-back reel and connected into said circuit in a manner to return the energy or the hold-back reel to the circuit.

of the type having a drawing reel and a holdbacl: reel and a drawing die intermediate the reelsand a drawing die beyond the hold-back reel comprising in combination with a source of power, fluid pressure energy translating devices connected to operate each reel, and a circuit connecting said translating devices in parallel with the source of power, whereby the drawing reel will be driven by its translating device and the hold-back reel will be driven from the drawing reel through the medium of the wire being drawn, the translating device at the holdback reel serving to apply a portion of the required driving torque to the hold-back reel whereby a predetermined back-pull from the second mentioned die is transmitted to the wire entering the first mentioned die and means for varying the displacement or one of said translating devices.

9. A drive system for a wire drawing machine of the type having a drawing reel and a holdback reel and a drawing die intermediate the reels comprising in combination with a source of power, translating devices connected to operate each reel and a circuit connecting said translating devices in parallel with the source of power, whereby the drawing reel will be driven by its translating device and the hold-back reel will be driven from the drawing reel through the medium of the wire being drawn, the translating device at the hold-back reel serving to cause a predetermined back-pull on the wire ente'ring the die and means preventing the holdback reel from overrunning the drawing'reel due to inertia when the drawing reel drive is discontinued. I

RUDOLF E. ESCH. JAMES ROBINSON 

